Early Electric Pick-ups for 78 rpm Records.
Some notes, jotting & reminiscences.
I have possessed and used old
moving-iron pick-ups and gramophones employing them since I was a child, long
ago in the 1950s. I once had a fair collection of such pick-ups and arms. But I
disposed of them 35 years ago when I moved house. Interest was only re-awakened
in seeing similar items for sale at the CLPGS Auction in September 2008. Some
of them were purchased, and it is mainly those I describe below. They came from
the collection of the late Ron Armstrong, which covered all aspects of early
sound reproduction. I never knew him, but would like to dedicate this web-page
to his memory.
A group of electric pick-ups, all from the Ron Armstrong
Collection. Clockwise from top left: 1.
‘AED’. Single coil, bakelite casing. 2. ‘HEGRA’. Single coil, nickel-plated metal casing. 3. ‘DAPTACON’. Single coil, metal casing, brown finish. 4. ‘J.B.
Woodroffe’. Uncased, magnet and mount nickel-plated. The interior structure of
1 & 2 is illustrated
below.
It would appear that this is a
somewhat neglected aspect of the history of 78 rpm discs and the devices by
which they were played? Or maybe not; perhaps it simply
doesn’t matter any more? Looking for references to them on the Internet
was overmasked by the fact that electric guitars have pickups, and countless
millions of people play electric guitars. Moreover, millions of people
apparently drive around in vehicles called ‘pick-ups’, so we gave up and
started this page anyway. 8^) As always,
all errors and misconceptions are our own.
Electrical recording on disc,
as we all know, became truly practical when Western Electric in the
Still, electrical reproduction was the next most obvious
thing to go for. Generally, U.S. Brunswick with their ‘Panatrope’ is credited
with developing the first practical electric gramophone in 1926. It was state
of the art, and naturally, very expensive. I have no idea what sort of pick-up
it had.
But before we launch into the
main subject of this page, it will be useful to review the origins of turning
mechanical vibrations into electricity, and back again. When Alexander Graham
Bell perfected the telephone in 1876, it relied on the very simple – and
therefore elegant – concept that magnetism could be converted into electric
current – and vice versa. I think
Michael Faraday had shown this, maybe half a century before. In its simplest
form then, the telephone, if spoken into, would convert the vibrations of the
speech falling on a thin flat diaphragm of iron, into a small electrical
voltage. And at the other end of the wires, an exactly similar device would
convert that small voltage back into sound, by activating the diaphragm of the
receiver. Thus, you had one device that could act as a sender and a receiver.
Not only that, but also you could both talk and listen at the same time – it
was, inherently, a ‘duplex’ system. (Considerable efforts were needed to make
the very simple electric telegraph duplex – though in time it became multiplex.
Of course, the range of this original telephone system was quite limited, and
soon the function of sender and receiver were separated, and a more specialised
device was used as the sender – or microphone, as it eventually became. But as
regards the ‘receiver’, this remained the same for very many decades. The
voltage, arriving, passed through a coil – or coils – of fine wire, and caused
varying magnetism in the metal core around which those coils were wound. This
magnetic field made to vibrate a thin iron diaphragm, which reproduced the
original sound. When I was young back in the 1940s & 1950s, our telephones
in the
The
‘headphones’ of the early radio broadcasting era, which started in the
First shot, the headphones
themselves. Second, one receiver. Third, the receiver with the ebonite earpiece
unscrewed. Fourth, the inside of the receiver with the flat iron diaphragm
taken off. (You slid the diaphragm off, never pulled it off. Doing that would
diminish the magnetism in the core!) Observe the two coils, wrapped in green
tape, placed round the thin magnetic core: these will become very familiar to
us as this page grows. Why two coils? Why not just one? Well, the magnetism
induced in the iron core by the tiny voltage, comes out at both ends of it. So
if we only had one coil, only one end of it would be near the diaphragm to make
the sound. The magnetism, the precious energy, coming out of the other end
would be lost. So, the core was bent round into a ‘U’ shape, so that both ends
of it were near the diaphragm, thus making best use of the energy. This also
involved winding each coil in the opposite direction or ‘sense’: but that’s not
important right now.
What is important, is that
headphones like this had been around for a long time. And so, experimenters
would have tinkered around with them and used them for other purposes. These
headphones were quite expensive, mostly because those little coils had many
thousands of turns of very fine wire on them & so were tedious to make.
But, as War Surplus after the Great War of 1914-1918, I dare say they became
rather less expensive. And so, it must have occurred to a number of people, to
use them as electrical reproducers of records. The most obvious candidate would
be cylinder records, as they were recorded with an ‘up-and-down’ motion –
vertically cut. It would have been a fairly simple matter to take an ear-piece
as above, and place a sapphire or glass stylus in the middle of the diaphragm,
then position the earpiece in place of the acoustic ‘reproducer’ those
phonographs used. But: what would one do then? What would one do with the tiny
signal that came out of your newly-invented electrical earpiece-reproducer?
Well, one might listen to it on a pair of headphones. But this would have been
a retrograde step! Phonograph cylinders had been listened to using an acoustic
stethoscope type of device back in the 1890s… Our intrepid inventor would have
needed to amplify his tiny signal and feed it into a loudspeaker in order to
attain really effective electrical reproduction. Alas, just after the end of
the Great War, there were still restrictions on the use of the newly-developed
valves (tubes) which could amplify sound: and in any case, valves being
‘cutting edge technology’, were very expensive.
Moreover, even loudspeakers themselves were still in their infancy, usually
consisting merely of an assembly as shown above right, coupled into a straight
or curved horn to amplify the signal acoustically. Still, I don’t doubt that
some people explored these elusive avenues in 1918 onwards. And they were the
first pioneers of electrical reproduction!
Now let us look at some of
these devices. I think we need two fundamental ‘classes’, as follows:
Class 1. Electric pick-ups sold as ‘add-on’
devices to the tone arm of existing acoustic gramophones.
Class 2. Electric pick-ups that came with their own
arm, which would entirely replace the tone arm of the acoustic gramophone.
In the earliest days, as we
would expect, Class 1 pick-ups seem to predominate.
Class 1 pick-ups.
In early 1927, a patent
specification was drawn up in
How did they work? We begin,
naturally, with our Class 1 pick-ups, the ones your
fitted to the arm of an existing gramophone. (Only three of the four pick-ups
illustrated at the top of this page are Class 1. The fourth, the ‘Daptacon’,
was included because it seemed to belong there. We have since obtained a
complete ‘Daptacon’ arm, and it actually is a Class 2 device, and so is dealt
with in its proper place, below.)
Above, we have a simple,
budget-price acoustic spring-driven gramophone. I’m not sure of its date,
sorry: I’m not really into gramophones, only records. Let’s say mid-late 1920s?
You can see easily that as the record rotated, the needle would follow the
lateral modulation – representing the sound – in the groove. Immediately above
the needle holder is a pivot, or fulcrum, from which extends upwards a thin arm
which is fastened to the centre of a mica diaphragm. Obviously, the tiny
modulations in the groove are increased by the fact that this lever – for that
is all it is – is longer above the pivot than it is below. It is in fact a ‘Class
1’ lever. A see-saw is a Class 1 lever; it has the fulcrum in the middle, and
the ‘plank’ balanced on it extends equally on either side. But this lever is
longer on the upper side, so it will increase, mechanically, the tiny
vibrations from the groove of the record. The flexible mica diaphragm will
vibrate correspondingly, and so set into motion the air-column which begins
behind the diaphragm, extends around the goose-neck, carries on through the
tapering arm and extends down into the wooden box, via a plywood horn, and ends
at the front of the gramophone in a rather pleasing, almost ‘art nouveau’
wooden grille (if there is such a thing as a wooden grille). Which is partly
why I bought this gramophone actually; but also the fact that it is a Sterno
machine, and Sternberg was a chap who was engaged in the Gramophone Trade in
this country for very many years and his life must have been a fascinating one,
but I don’t think anybody really knows much about him. The main point is, that
the vibrating air column which began small, was appreciably bigger by the time
it came into your living room. So you could hear & enjoy your 78 rpm
records.
Now, gentle reader, it is time
for two apologies. 1. I have just described, roughly, how an acoustic
gramophone works, and you may well say that this has nothing to do with early
electrical pick-ups. And you would be perfectly right. 2. I am writing a very
big lot of verbose stuff, which could be expressed far more concisely. Again,
you are correct, and I apologise for both transgressions. Unfortunately, I
actually like writing great long
rambling things; though you will be relieved, possibly, to learn that most of
it never gets uploaded to the ’net…
Above all, the acoustic
gramophone shown above still has a role to play in our story. Because, as we
said, the metal tenon on these early electrical pickups enabled you to fix them
on your old acoustic gramophone. Above you see the bakelite-cased ‘AED’ pickup
in place on the same gramophone. The wire coming out of the back led away to
whatever you were using to amplify the signal. Later, we’ll go into exactly
what that apparatus might have been. This pickup was made by the AED company,
probably around 1930 or a bit later. I’d hazard that the letters stood for
‘Acoustic and Electric(al) Developments’. The internal assembly is shown at the
right, above. This is a horse-shoe magnet with a single coil. AED seems to have
been a Limited Company belonging to an inventor & electronic developer
called Bowyer-Lowe. (More on this below). Note the interesting Trade Mark
stamped on the magnet; what is it? A
fish?
Little was found on line about the next
one shown above, which was made by a company called HEGRA. This might be because
HEGRA, nowadays, is an acronym for High Energy Gamma Ray Astronomy, which –
however intriguing the subject may now be – simply did not exist when the
pick-up was made, probably around 1930. Besides which there is a Hegra hotel in
But we have saved the best
until last. And the reason is, that this beautiful, elegant and very early
British J.B. Woodroffe pick-up of ~1927 (which disdains, in its simple dignity,
to conceal itself in any casing) illustrates perfectly how these devices
worked. As you can see, the needle was moved from side to
side by the lateral groove of
the disc. The needle is mounted at the lower end of the ‘armature’ as it was
called, and this armature is pivoted in its centre. The armature was made of
iron, a magnetic material. The axis of this pivot is the set-screw which is
visible in front of its brass locking ring. The position of the entire armature
was also adjustable: this was achieved by the thick threaded rod you see,
rigidly anchored to the right-hand arm of the horse-shoe magnet by the big nut
on the right, the adjustment being secured by the knurled lock-ring on the inside.
So: if the groove took the needle to the left, the lower end of the armature
approached the core of the lower coil, inducing a current in it; while
simultaneously the upper end of the armature would recede from the core of the
upper coil, also inducing a current in it. (It is a change in a magnetic field, not the presence of a static field,
which induces a current in a coil.) And because these two coils were wound in
opposite directions, the voltages produced were added together. Two bites of
the cherry, one might say! Movement of the armature to the right produced the
converse situation, but which still produced a voltage. So all in all, the
complex wave-form of the groove produced a corresponding voltage. Wires would
have been connected to the two nickel-plated pillar terminals just below the
signature trade-mark, and those wires would have been connected to our
amplifier.
The other examples further up
this page work in exactly the same way, though they only have one coil.
Before proceeding, we must
address a very important point. Resonance. Any mechanical assembly has a
resonant frequency. You have probably driven your car over those
thickly-painted yellow lines across the road that are intended to make you slow
up when approaching a traffic island? They often produce a distinctly
unpleasant bumping up and down of your car – and you! Like anything else
mechanical, your car has a ‘resonant frequency’, and those thick lines are
designed to set your car’s suspension into resonance. Each stripe you drive
over can add its impulse to the previous one, so that the resonance builds up,
and tells you, in no uncertain way, that you really must slow down. For example, it seems that the resonant
frequency of my car is about 5 or 6 ‘cycles per second’, or Hertz (Hz) as we
now call them. It is a most disagreeable sensation to be vibrated up and down
at such a frequency! A car is relatively big and heavy and so has a low
resonant frequency. The smaller the mechanical system, the higher it is. So the
resonant frequency of a small armature in an electric pick-up would be quite
high. Several hundred Hz, possibly 1,000 Hz or so. The trouble is that this
frequency is slap bang in the middle of the range where our music is. So our
electric pick-up will produce a far higher output around this frequency than
any other, because the vibrating armature ‘prefers’ to vibrate at (or even just
near to) its resonant frequency, compared to all the others. This results in
distortion of the music we want to listen to.
How can we make our electric
pick-up ignore this particular frequency, and reproduce all frequencies evenly?
Well, we must ‘damp down’ this resonant frequency. Actually, persisting with
the motor car analogy, that it exactly what the shock absorbers on your car do.
Otherwise, your car could easily begin jumping up and down from time to time in
any case – not just when safety-stripes are painted on roads.
Here you see the other side of
this Woodroffe pick-up, and all is obvious. The curly orange thing wrapped
round the two slotted brass pillars is a strip of thick rubber. You can see the
smaller screw-heads which anchor it to the pillars. What you can’t see (because
it’s behind the yellow wires) is another screw which also anchors the rubber
strip to the top of the armature. The purpose of this rubber suspension is to
encourage the armature to respond equally to all frequencies, by preventing its
tendency to resonate at its ‘preferred frequency’. I have looked at one or two
other patent specifications for early pick-ups that can be found on line, and
it would seem the method of suspension, or damping, is usually their main
subject. After all, the basic idea of converting mechanical vibration into a
voltage by a moving armature was really very old by the 1920s, so you couldn’t
patent that. But you could patent a
novel method of damping the armature – and that is what the inventors of
subsequent ‘moving iron’ pick-ups usually seem to have done.
Very well. Now that we had our
little audio voltage that corresponded to the music on our 78 rpm disc, what
did we do with it? Why, we fed it into an amplifier. The output from this
amplifier was connected to a loudspeaker, and Lo! the music poured out,
refulgently, into our living room. But where did we get an amplifier in the
late 1920s & early 1930s? If we were fairly prosperous in those times and
had a radio set, then we already had an amplifier. The last 
valve (or two) in our radio set had the purpose of amplifying a
small audio frequency voltage. True, that small voltage had been derived from
the radio waves that our aerial had picked up; but one small audio frequency
voltage is – generally speaking – much like any other small audio frequency
voltage. So by the mid 1930s, most radio sets were equipped with ‘pick-up’
input connections on the back, and we plugged our wires into those.
However, if we were an
‘audiophile’ with a couple of weeks’ wages going spare, then we would construct
a dedicated audio amplifier for our electric pick-up. Here is a circuit diagram
for one. It came in a leaflet with another of these ‘add-on’ pick-ups, the
‘Phonovox’, manufactured by The Igranic Electric Co. Ltd. Unfortunately, the
leaflet is not in good condition otherwise we would reproduce it in its
entirety. But the circuit diagram speaks for itself. Naturally it uses all
Igranic components, or at least all those necessary that Igranic made. The
voltage from our pick-up goes into a step-up transformer. A volume control is
connected across the secondary of this, which feeds into the grid of the first
valve. The amplified signal passes via C1, the DC blocking condenser – ulps!
capacitor I should have said – into the second valve. The signal emerges from
this into another transformer, and proceeds thence to the output valve V3. The
choke O.C. permits the high tension (DC) to reach V3, but prevents the audio
(AC) from passing back that way; the audio therefore passes through C2 (which
blocks the DC) to the Loudspeaker connections LS.
Note that several possible
sets of valves are listed. The 2 volt range were of course for people who lived
in houses where there was no mains electricity supply. If you are young, dear
reader, you may be surprised to learn that there still existed large areas of
this country, as recently as the late 1950s, which had no mains electricity! In
such cases, you ran your radio set – and possibly even your Igranic gramophone
amplifier – from a high-tension battery (up to 120 volts), and a 2-volt
lead-acid accumulator to run the valve filaments. 4 volt & 6 volts valves
ran from the AC electric mains via a step-down transformer. Notice there is no
tone control. I’m sorry, if you wanted to blow the windows out of your house or
drive your neighbours to distraction with ‘mega bass’, that simply was not
possible around 1930! By the way, the three connections GB-1, GB-2 and GB-3
were connected to another battery, the ‘Grid Bias’ Battery, which was necessary
to make the grids of the valves somewhat negative with respect to the incoming
signal. That also is not important right now.
Another Class 1 pick-up with
an interesting design feature was this ‘Radio Gram’. Who made these we do not
know. The ‘cup sleeve’, which is simply fastened to the bakelite body by an
eyelet, is of generous diameter, so it would have fitted most acoustic gramophone
arms. The vertical screw drove down a simple U-shaped clamp which would secure
the pick-up to the tone arm. The internal structure is quite simple, but
featuring ‘tapering pole pieces’ (more on this far below). What is interesting
about this one is the damping of the armature. In the third picture, you see
screws which have two wire springs between them. This probably means that the
armature is damped by these springs? This is analogous to the springs used on
acoustic sound boxes. Remember, the armature requires both a suspension (a
fulcrum), and also some damping to avoid resonance. Where the suspension is in
this design is unclear; I prefer not to dismantle these things in order to find
out. IF the suspension is the sort of
rubbery disc around the needle hole, indicated by the yellow arrow, and which
locates in a hole in the bottom of the bakelite (or ebonite?) casing… then, I
think, we would have a truly novel pick-up! Namely, one which employed a Class
2 lever, as opposed to the Class 1 levers (a see-saw) that most of them use,
and which, along with their unusual spring damping, would doubtless have been
the principal subjects of the patents for which the makers had applied. (‘Pats. Pen.’ = Patents Pending.)
Even ‘Mighty HMV’ did not
scruple to market a Class 1 pick-up. This one was called the ‘No. 11’, and came
as an outfit, with connecting leads and volume control. Here it is seen in
place on an Electrola gramophone, which is simply the German version of an HMV
Model 109. This gramophone normally used the HMV No.4 sound box, and was
current until the early 1930s (sorry I am so vague on the details of machines…)
The point is, that the tone arm of the 109 was relatively small in diameter, so
an adaptor sleeve is present in this example of the pick-up. HMV even
thoughtfully provided a couple of chromium-plated clips, to keep the connecting
wire from getting in the way. Incidentally, I would not dream of playing my
rather nice OKeh of Frank Trumbauer’s ‘Borneo’ on an acoustic machine, still
less with one of these extremely heavy electric pick-ups; it is simply there a
as a photographic ‘prop.’! 8^)
Above we see the black
bakelite pick-up with its (rusty) securing screw. Then the internal structure:
the usual horse-shoe magnet, the single coil and the red rubber damping at the
top of the armature. This would have been very easy to replace. One assumes
that the suspension of the armature was on the axis of the needle screw, and
might have been the simple mechanical form. The coil is held in place by a
couple of dollops of varnish. (See also the HMV No.15, dealt with in Class 2
below.) On the right is seen, we think, the complete outfit: the pick-up
itself; its cable, terminating in a three pin plug; the volume control, which
is a simple potentiometer (more on these below); another three pin plug on a
much longer cable which led to your radio set. The plugs are not polarised, so
will go in either way. This isn’t a problem, as we have here a ‘twin feeder’
with a separate earth in the middle. The letters on the input are: P – E – U.
Pick-up, and Earth. Or Pick – Earth – Up, strictly speaking. The letters on the
output side are B – E – C; E is clearly Earth, but what B & C are: who
knows? Also, there are two of the chromium-plated ‘cable tidy’ clips, which we
assume came with the outfit. If they didn’t, others would have hastened to
supply them, as even to this day you can buy ‘cable tidies’ for the plethora of
cables that lurk under your PC work station! I don’t use ’em myself; I tend to
dismantle everything every four months or so, remove the now-redundant leads,
stuff them in a drawer (you never know, they may come in handy some day – “Save
The String” and all that), then vacuum up all the dust & cigarette ash that
has gone down there. While this is a tedious procedure, it is also a most satisfying
one, redolent of a Ritual Purification; and we all need one of those from time
to time? 8^)
I think that’s about it for
our ‘Class 1’ pick-ups. There are of course many more
waiting to turn up at car boot sales & on eBay, and as we acquire them, they
will get illustrated & written up here. Accordingly, we now move on to:
Class 2 pick-ups.
That is, those which were
marketed as an integrated pick-up and arm, mostly from the early 1930s onwards,
which you could buy and fasten on to your acoustic gramophone, entirely
replacing its acoustic tone arm – though I dare say, some people kept ‘hybrid’
gramophones, which would work either way!
1. The Bowyer-Lowe Mark IV.
This has British patent number
396,875, which dates to the early 1930s. Bowyer-Lowe had a company which made
all manner of radio and electrical components. This arm is extremely well made.
It rotates on a ball-race, and needs no ‘arm rest’, the front of the rotating
bracket serving this purpose. The counterweight at the back is not adjustable,
but balances the arm well. Changing the needle – which of course in those days
you did after playing every record – was very convenient with this arm. You
simply rotated the head 180º
anti-clockwise, as seen below.
The internal structure is the now-familiar
horse-shoe magnet, with a single coil in which the armature moves. The playing
weight, as you see, was 95 grams, which was comparatively modest in those
times.
Also illustrated here is a
cardboard box which once contained a ‘Bowyer-Lowe’ “Beta” pick-up, with
adaptor. We do not know what this ‘Beta’ pick-up was, though it may well have
been the bakelite ‘AED’ one pictured above. What is interesting is that ‘AED’
and ‘Bowyer-Lowe’ are effectively synonymous. Possibly this may represent the
inventor himself, Bowyer-Lowe, working through a Limited Company that would
promote and sell his inventions, while leaving him free from the trammels of
everyday business to pursue his researches?
2. The Meltrope Electric Pick-up and Arm.
Originally, ‘The Meltrope’ was
an extremely successful acoustic sound-box. You used often to find them years
ago. My own opinion – though as always I am probably wrong – is that whoever
designed that sound-box was trying to take a ‘mimimalist’ approach. That is,
not only to make a sound-box that sounded good, but was also easy (and cheap)
to manufacture. Whoever Meltrope were, they seem to have been wildly successful
in their aims. Their stylus bar was balanced on four ball bearings that were
sandwiched between the front cover of the sound-box, and its body. Other
acoustic sound-boxes generally ‘balanced’ their stylus bar with a pair of
opposed leaf-springs, which often required delicate adjustment. There was of
course, much ‘mystique’ in those early days about sound-boxes and their
‘tuning’. How the stylus bar was balanced and adjusted: what size & shape
of horn was it to drive?: the material used for the diaphragm: its thickness,
its treatment before use: which prayers to offer up (& to which Gods)
before assembling & adjusting it &c. You know, some things never
change? For example, it’s self-evident (and audibly perceptible) that thick
wire from your present-day amplifier to your present-day speakers is better
than cheap, thin ‘bell-wire’. But belonging as I do to a previous and now
obsolete era, I find some difficulty in going along with the hype that attaches
itself to really advanced modern speaker cables. Silver cables? Silver is a
very good conductor of electricity to be sure. Better than copper, certainly!
But is the difference really that
audible? If so, I fear you have no option other than to proceed to thick Gold
speaker cables: then to thick Platinum speaker cables, and from thence to thick
Palladium speaker cables. And those really will set you back a bit, money-wise!
But I digress… When electrical reproduction came, Meltrope must have seen the
writing on the wall. Good as their acoustic sound-box was, the move to an
electric product would have been unavoidable – so in order to keep their foot
in the door, they had to come up with some really convincing replacement for
their highly-rated acoustic sound-box. Here it is:
Meltrope, I think, were taking
no chances. The patent numbers apparently date from 1927 & 1928, and are
attributed to
Its basic structure is
‘traditional’, if we may apply that term to such new technology. As usual, a
horse-shoe magnet, with cross-piece, which envelopes a single coil of fine
wire. I particularly like the red and green curly wires that connect the coil
to the thick leads that took the signal down the arm. These ‘curly wires’ to be
seen in so many early electrical pick-ups are certainly not for decoration,
however attractive they now seem to us. No: any vibration was absorbed &
dissipated by them, and so repetitive stresses that might fatigue & break
the joints were avoided, as well as unwanted resonances that might result from
the use of stiff wires. Another very interesting feature is the small size of
the rubber suspension to damp the armature. You see one end of it in the
picture at left, the other end at the right. It is nothing more than a short
length of thin red rubber tubing. Contrast this to the huge thick (though
adjustable) rubber damping strip of the Woodroffe pick-up above. We clearly
have two very different approaches to this two-edged problem. A suspension has to be provided for the
vibrating armature; but also, the damping
of its mechanical resonance must be dealt with. Woodroffe’s pick-up has a
purely mechanical suspension, and relies on its adjustable thick rubber for
damping.
his needles in aluminium collets. You can see in the pictures
above, the thing the needle goes into is a metal tube. However, circa 1930, there were quite a variety of
‘gramophone needles’ in current use. Thin ones to play records quietly (they
flexed more & transmitted less energy onto the pick-up); medium ones, which
were… well, just medium; and loud ones, which were thick & rigid & sent
more energy into the pick-up. [Here, an aside: gramophone needles were actually
‘pins’. A ‘needle’ has an eye, through which you thread your cotton, yarn or
whatever, right? A gramophone ‘needle’ does not have an eye, and is therefore a
pin. Accordingly, through all those years when countless billions of these were
made, all the manufacturers duly referred to them, inside the factory, as
‘pins’.] But besides these, were non-metallic
needles – which were much favoured by high-class gramophone enthusiasts of the
time. These were the ‘fibre needles’, which reduced wear on records because
they were softer than metal. There is no space here to go into all that sort of
stuff. There is more than enough material in that subject for a Doctoral Thesis
– indeed, I wouldn’t be surprised to learn that one or more has actually been
written. If not, I commend it to you as a possible subject. The main point
(sorry!) is that many (though not all) of these fibre needles were triangular
in section. How then, was the Meltrope to cope with this great variety of thin,
medium and thick steel needles, plus some triangular ones? The answer was
absurdly simple: a range of at least seven collets was provided, as shown
above. In order to take this photograph, I simply stood them up in a group,
which was quite difficult as they kept falling over & rolling about. But
oddly, they have turned out in some sort of order. The three on the left which
have the smallest holes, are probably for thin, medium & thick steel
needles. The two at back right are obviously for the triangular fibre needles,
and the two at front right are probably for round non-ferrous needles – ‘thorn’
needles as they were called. Years ago, I tested thorns from a hawthorn hedge
in the garden of my old house, and they worked quite well. In the
A SUGGESTED DOPE FOR FIBRE NEEDLES.
The object of doping fibres
is to make the points tougher so that they are less susceptible to breaking
down in the heavy passages of a record, and so that the reproduction is cleaner
and the volume slightly greater.
Make a saturated solution of
Gum Arabic and water and a saturated solution of Potassium Bichromate and
water. When the fibres are ready for doping—not before—thoroughly mix two parts
of the Gum Arabic solution to one part of the Bichromate solution in a dark
room and leave the needles in the mixture, also in the dark, for at least
fourteen days. Then remove and wash the fibres lightly in water and wrap in a
cotton duster to remove surface moisture. Allow the fibres to dry in the
sunshine or any artificial ultra-violet light such as that used by draughtsmen
for taking blue-prints, or even one of the domestic "sunshine"
appliances now on the market. When the needles are absolutely dry clip and use
in the ordinary way. But remember the "don'ts."
Don't mix the two solutions
until the fibres are ready for doping.
Don't expose the mixture to
light.
Don't dry the needles in
front of a fire or in an oven.
The above is obviously
commendable, even if it bears a distinct resemblance to mediaeval alchemy: the
ritual of which was at least as important – indeed often very much more so –
than the actual physical & chemical processes involved. I mean, if your 78
rpm records didn’t sound better after you had prepared your fibres or thorns in
this time-consuming manner, then I really don’t know what to say. I am puzzled
though, by the phrase: ‘When the fibres are ready for doping—not before—’ How did people know when the
time was right? They do not tell us when this is; so it must have been common
knowledge circa. 1932, but has since
been lost to us. Did gramophiles of the time, lighting their after-breakfast
pipe, stroll around the garden contemplating the lupins & hollyhocks, then
after studying the sky for some time and possibly noting the propitious flight
of certain birds, call back to the house: “Cynthia darling! It’s time to dope
the thorns! Be a sweetie and mix up the Gum Arabic and the Potassium
Bichromate, won’t you, eh? I’ll be in presently.”?
3. An Electrical Arm of Unknown Make…
This arm is interesting in
that it seems to be designed specifically for the ‘side-fixing’ type of
electric pick-up. That is, the ones that fitted into the pre-existing arm of an
acoustic gramophone. Accordingly, it must be quite early. It also has a rather
‘scratch-built’ appearance, though there would have been a great deal of effort
involved in this. It’s made of aluminium or some alloy thereof. There is no
identifying mark or any kind on it. A clue, however, lies in the rather
‘weathered’ Woodroffe pick-up attached to it. This is firmly fixed in place by
slight corrosion, and has defied all efforts to loosen it, even using WD40
& so on. I have given up trying, as something will undoubtedly break. The
pick-up has clearly been fixed to the arm for a very long time. So, using
Occam’s Razor, we have a very old arm, and a very old pick-up; so we must
assume that they belong together. And in view of the absence of maker’s name,
model or patent number, it’s either a 
prototype or a limited-run specialist arm. From the photograph at
right you can see the arm pivot is simple in the extreme, but it works well.
The merest drop of oil would keep it sweet. Adjustment of the playing weight is
simple but effective. The knurled nut N is used to compress a spring which
bears down into a hollow in the arm behind the arm pivot P. It is possible to
get the playing weight down to zero so that the arm ‘floats’. Unscrewing the
nut increases the playing weight. As with modern arms, one must be careful not
to use too small a weight. A weight of around 100 grams (a quarter of a pound)
may seem horrifically heavy to us today! But any attempt on the part of a 1930
gramophile to reduce this weight significantly would have resulted in the
needle ‘chattering’ in the groove & so causing serious record wear as well
as poor reproduction. The needle absolutely must bear down into the groove with
sufficient force (but no more, to be sure) to enable the pick-up armature to be
driven efficiently; and that is as true today as it was in 1930. When I worked
in the domestic audio trade in the early 1970s, customers would sometimes
proudly say they had persuaded the modest Shure M-44 cartridge to track at 0.75
grams. My reply needed some tact, because that weight simply wasn’t enough! The
M-44 required about 1.5 or 2 grams (I forget now) to track properly, so they
would be getting just the same sort of effect as our 1930 person. The term
‘needle chatter’ had been long obsolete, but increased wear on their LPs &
a less focussed sound would still have occurred!
One thing which is very
important about arms is their height in relation to the turntable.
Traditionally, they have always been required to be parallel to the surface of
the record. In the case of this arm, when it is level, there is only just over
half an inch (~1.5cm) beneath the needle. This isn’t much to accommodate the
height of an old-style turntable. It might have been necessary to mount the arm
on a spacing block to raise it up. By the way, you can’t see the wires in this
arm; the ends have been cut off. But it is ordinary ‘twin flex’, and runs under
the arm which is, in effect, an inverted trough.
4. An important accessory: The Volume Control.
We have seen how these early
pick-ups were connected to an amplifier, and that a volume control was needed.
(R1 in the circuit diagram above) Even if we were plugging our pick-up into the
back of a radio set (which usually – though not invariably – had a conventional volume control) another
one might still be necessary because the pick-up could deliver too high a
voltage into the audio amplifying stage(s), causing overload & hence
distortion. One quite common pick-up arm, made by Harlie, cleverly incorporated
a volume control into its pivot, the knob being on the top of it. Eventually we
will obtain one of these & write it up. This has now
been done – see 5 below… But if you just had an arm like those we
have dealt with above, you would almost certainly need to purchase a volume
control. This was simply a potentiometer: that is, a resistance which you could
tap up and down in value by rotating a knob, which adjusted an arm (the wiper)
which went around the track of the resistance - but a picture is worth a
thousand words…
Left. A complete unit mounted in a bakelite
housing, which you would (carefully) screw down in a convenient place. The
wander plugs on the pick-up lead went into the two holes at the top, and the
flying lead seen at top right would go into the radio set. This unit carries no
maker’s name. These black knobs with the arrow were extremely traditional in
the later 1920s & 1930s. Centre. A smaller, panel-mounting potentiometer, but still with a
traditional knob. Right. The underside of the same
device, which reveals that it was imported here from the U.S.A. Scratched into
the casing lower right is “1/4 MEG” – that is, one quarter of a Megohm, or
250,000 ohms, the total resistance of the track. The devices illustrated here date
from around 1930 – 1934 we think.
5. The Harlie Pick-up Arm.
As mentioned above, these sold
well, and happily were able to acquire one, thanks to a helpful seller on eBay.
The knurled knob is marked ‘Max – Min’, and the cable is tinsel wire, very
flexible. This is a handsome arm with its pleasant contrast of bakelite and
chromium plating. The ‘works’ are shown, and are just as we would expect by
now. This arm probably dates from the early 1930s. One notable feature is the
stepped laminations. (These are thin sheets of metal stacked & clamped
together – magnetism is transmitted better by a layer of thin strips rather
than a solid bar.) The brass nuts holding them tight are painted with a brown
coating to stop them coming loose. Above the coil you see that each lamination
is slightly longer than the one in front of it, and the only the longest one(s)
come right up to the armature – you can just see this coming out of the centre
of the coil. This is a good design feature, because the magnetic field from the
horse-shoe magnet is concentrated just where it is needed – i.e., each side of
the armature. We are very much in the Art Deco period at this time, and the
bakelite front cover reflects this.
6. The Cosmocord Pick-up Arm.
The Cosmocord company were based in
7. The ‘Daptacon’ Pick-up Arm.
We acquired a ‘Daptacon’
pick-up head from the Ron Armstrong collection; this is illustrated right at
the top of this page. At that time, we were not sure how it fitted into ‘the
scheme of things’. But it turned out to be the detached head from a complete
assembly, so really belongs in our Class 2. As you see, it is of simple
structure, and so probably was budget priced. Also, you can only raise the arm
to an angle of abut 40 degrees, and the head does not rotate for the fitting of
the new needle, which means you have to more or less ‘fiddle’ the needle into the
socket – unless you want to kneel down so that you can see what you are doing.
The head itself is of all-metal construction, relatively unusual. It has not a
horse-shoe magnet; instead, it has three separate bar magnets in an inverted
‘U’ shape. All these things, we feel, tend to indicate a date further into the
1930s than most of the other examples on this page. Let’s guesstimate 1934/6?
Also, there is no provision for the lead to pass through the flange of the
pivot. A hole would have to be drilled in the motor board, and the lead pass
down to the radio chassis or amplifier. This again indicates a later date?
8. The Marconiphone Pick-up Arm.
Well, we have to say, that
this picture is just as much about the box as about the arm! Resplendent in its
Art Deco design and ‘chemical red’ colour, the box houses an example of what is
probably the most ubiquitous pick-up arm of the mid and later 1930s. By this
time, the ‘domestic audio’ side of Marconi was of course part of EMI, which
principally included HMV and
At the left is the arm,
looking a little floppy & folorn without its arm rest! Next is the
underside of the pick-up. The head did not rotate, but the arm lifted up
through a large angle so that fitting a new needle was quite easy – you could
see what you were doing. Notice the five screw-holes: they are filled with a
thick varnish or solution of shellac – much the same thing. This, we suggest,
was not to stop the screws working loose by vibration (though it would have
served that purpose), but as insulation to prevent dangerous voltages, up to
250 volts, appearing on the pick-up head. Many radio sets of the time had a
‘live chassis’, as it was called. Without going into detail about this, in some
cases the mains voltage could appear on outlying accessories such as a
gramophone pick-up. All five holes are here filled. This means that this
pick-up has never been opened; or if it has been, the holes have been re-filled
with insulating sealant. In any event, we undid the central screw, so you can
see the ‘innards’ on the right. These are at an angle, but still consist of a
horse-shoe magnet and the inevitable coil of fine wire. The red rubber can be
seen, where it damps the upper end of the armature, just as in the HMV No.11
pick-up shown earlier. But there is a startling new feature here! There is
ANOTHER coil above, held in place by a brass strip. What is this for? Well, I
think it is there as a ‘hum-cancelling’ coil. When Class 1 pick-ups were fitted
to acoustic gramophones, there was no problem with ‘AC mains hum’ being induced
into the pick-up: those early turntables were usually driven by spring motors. But later, when turntables were driven by AC
electric motors, there was a distinct possibility that the alternating magnetic
field from those motors might reach the pick-up, the action of which, as we
have seen, depends on a varying magnetic field. This ‘AC hum’ would combine
with the musical signal from our record, and spoil it. So probably, this
pick-up has an extra coil, which is there solely to ‘intercept’ this rogue AC
hum. Above all, this coil would be wound ‘in the opposite sense’ to the main
coil, so that the hum induced in the main coil would be cancelled out when
their outputs were combined. Yes? Er… well, it’s not a bad suggestion; I must
do some more research here….
9. The HMV No.15 pick-up.
This pick-up was an integral
part of an arm, or even an early HMV ‘record deck’ – we are not sure yet – but
has been detached, possibly to be kept as a spare part. You obviously turned
over to change the needle; there are two ball catches on the brass sleeve, and
a pin would engage the slot, and limit the travel. Incidentally, one of my
great-grandfathers, Charlie Holder, invented the ball-catch. This was in
This is
nominally the end of this page, with a couple of concluding paragraphs below.
But as at February 2009, we are extending this page to cover two ‘home
recording devices’ contemporary to some of the above items. We’re just
‘parking’ the following here temporarily – there will eventually be another
page covering the various home recording devices we know of.
1. The Ekco ‘Radiocorder’
Home Recording Device.
This apparatus cost a whopping
Five Guineas, (£5.25) back whenever it was around – which would have been, yet
again, the early 1930s I should think. That was something like two weeks’ wages
then? But still, you got quite a ‘chunky’ set of things for your money! It is
obviously in quite good condition, but still needs a little restoration, which
is why it can’t be assembled properly in this photo. In the background is the
playback arm. The hollow cylindrical mount and the two thick pins locked into
the bakelite mounting block on the right – the thing with the three little
pillar terminals on it. This mounting block had a height adjustment bush – it’s
being used here to prop up the back left of the recording assembly! To record,
you unplugged the playback arm, and replaced it with the recording assembly. So
the right hand end of the assembly was firmly anchored. The left hand end, with
the rubber wheel, then rested somewhere near the centre of the turntable. As
the turntable rotated, it drove the rubber wheel, which operated the horizontal
feed-screw, and thus traversed the cutting head over the disc, which was of
soft aluminium. I should have said that the same head is used for recording and
playing. It has two long pins on the back of it, and so is interchangeable.
About seven thousand words ago, I pointed out that the first telephones would
act as a receiver or a transmitter; and so will these moving-iron pick-ups!
Although in good condition, most of the cast parts are of ‘pot metal’, which in
time expands, & the two cylindrical mounts have got too big to go into the
base. It will be necessary to take them down a little with emery tape. On the
left, above, is the inside of it and suddenly all is clear – it is identical to
the Harlie pick-up shown above. The same reddish-brown lacquer to hold the
nuts, the same laminations, the same damping – and of course the same style of
front cover, albeit in tasteful mottled green bakelite. Look: here are all
three covers together:-
The Cosmocord pick-up is
different in structure, but it seems clear we have a common maker here. I
wonder who it was? We shall have to find out.
2. The Harlie Home Recording Device.
This unit is slightly
distressed, but its function is plain. We have called it a Harlie device
because it has a Harlie head on the front, which is internally identical to the
other Harlie & the Ekco. The transfer on the vertical pivot is currently
illegible. Obviously, the loose pulley at left is secured to the centre spindle
of the turntable with the little wing-nut. The flexible spring belt – like
those on cine projectors – then drives a corresponding pulley in the base of
the pillar. A bevel gear in turn drives the horizontal feed-screw. In due
course it will be restored.
The End!
There follows two short paragraphs which will eventually be put
back in their proper place.
By the way, what was the
output in volts, of these early pick-ups *? What was their frequency response? And
what was their impedance? Well, this page is long enough already. If you have
read this far and have any interest in the subject, it will be easy for you to
research these matters on-line! (As regards simple DC resistance, the Wodroffes
are just over 2000 ohms. The others, with the single coils, range between 1000
& 1200 ohms)
As to what they sounded like,
that’s another story altogether. All the rubber damping and suspensions of
these units has become rock-hard after 80 years. If you played a record with
one of these today, it would certainly damage your record. Moreover, magnetic
materials have been vastly improved since those times, and these horse-shoe
magnets will probably have lost a good deal of their field strength over the
years, and the voltage output depends on the magnetic field. The only true
evaluation of this type of pick-up would require re-magnetising of the
horse-shoe to the same level as it
had originally. How do we know what that was? I certainly don’t know. The
logical assumption would be that they were magnetised to their saturation
level, but even that would have to be checked out. Similarly, the
damping/suspension rubber would need replacing by a material with exactly the same elastic properties as the
original rubber. Which we can probably never know! Besides, what they sounded
like would depend on what amplifier you fed them into, and above all, what sort
of loudspeaker you used. No; I’m afraid the quest is rather useless, as is
attested by the lack of general interest in these items. As I remarked at the
top of this page, early electric pick-ups are, apparently, very much the
‘Cinderella’ of record-playing equipment! <8^(
* The frequency response chart
of the Marconiphone, a link to which is given above, indicates that its output
was all of 1.7 Volts at 0 dB. Hence the need for an intermediate volume control…
Page first uploaded 10th November 2008.
Revised 8th January 2009.
Revised 2nd February 2009.
Revised 5th April 2009.